I hardly ever tuck in my shirt unless I am wearing a suit. I usually choose my shirts to be slim with relatively short shirt tails, which I think looks best. Come to think of it, a slim shirt nearly always looks better than a blousy one. I also find that untucked shirttails look better than a squared bottom, generally. Occasionally, I'll tuck in my shirt if I have on a pair of slim, flatfront pants and a cool belt, to show it off. I have never tucked a shirt into jeans. But then again, I am not German, nor have I ever been a fan of Nascar.